CN112197693B - Detection device and method for spot welding nugget form - Google Patents
Detection device and method for spot welding nugget form Download PDFInfo
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- CN112197693B CN112197693B CN202010894894.9A CN202010894894A CN112197693B CN 112197693 B CN112197693 B CN 112197693B CN 202010894894 A CN202010894894 A CN 202010894894A CN 112197693 B CN112197693 B CN 112197693B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/28—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring contours or curvatures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
- G01B7/26—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring depth
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
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Abstract
The invention relates to a detection device for the form of a spot welding nugget, which comprises a plurality of magnetic sensors and a calculation module, wherein the magnetic sensors are arranged in an array form of m rows and n columns, the size of the array form of the magnetic sensors is larger than that of the spot welding nugget to be detected, the magnetic sensors are used for detecting the magnetic induction intensity, and the calculation module determines the shape of the spot welding nugget according to the magnetic induction intensity detected by each magnetic sensor and calculates the parameters of the spot welding nugget. The invention also relates to a method for detecting the form of the spot welding nugget by using the detection device. The invention can detect the size and the depth of the nugget of spot welding.
Description
Technical Field
The invention relates to the technical field of spot welding quality detection, in particular to a device and a method for detecting the form of a spot welding nugget.
Background
The resistance spot welding has wide application, and the spot welding structure has the advantages of light weight, high static strength, good reliability, stable performance, easy realization of automation and the like, and is a main connection mode among metal plates. The spot welding applies and maintains certain pressure to the welded workpiece through the electrode to ensure that the workpiece is stably contacted, then the current output by the welding power supply passes through the welded workpiece and the contact surface of the welded workpiece, generates heat, increases the temperature and melts the local part of the contact point to form a welding point.
With the development of spot welding technology and automatic production lines, enterprises have higher and higher requirements on the quality of resistance spot welding spots, and the requirements on detecting the diameter of spot welding and detecting the shapes of a welding core such as volume are required, so that the spot welding quality is comprehensively evaluated.
The quality assessment of spot welded joints generally has their corresponding evaluation criteria in different industries or uses corresponding regulations depending on the specific application in which they are used. Because the forming process of the resistance spot welding nugget is closed and invisible, the strength of the spot welding joint cannot be directly determined from the appearance after the spot welding joint is formed, and the reliability of the quality of the spot welding joint is generally determined by observing the shape, the size and the surface color of the spot welding joint by naked eyes when the quality requirement is not high.
When the quality requirement is high, destructive testing or nondestructive testing is generally adopted. The destructive detection is to split a test piece, measure the nugget diameter of a sample and evaluate the welding quality, but the method causes a certain waste of resources. The nondestructive testing method mainly comprises the following steps: welding parameter monitoring, infrared detection, X-ray detection, eddy current detection, and ultrasonic detection. The welding parameter monitoring method mainly utilizes a special sensor to monitor and control welding parameters in real time, the monitoring parameters comprise welding current, welding voltage, contact resistance, electrode pressure, electrode displacement and the like, the welding spot quality is evaluated by establishing the relation between the welding parameters and the size and defect distribution of a welding spot nugget, and the detection method is generally low in detection precision and cannot directly reflect nugget quality information. The infrared detection method mainly utilizes an infrared thermal imager to detect the temperature of the resistance spot welding joint in real time and detects the quality of the welding spot through the change of temperature distribution. The X-ray detection method is mainly characterized in that energy change generated by penetration of resistance spot welding joints by X-rays is utilized, and the size and defect information of welding points are evaluated through analysis of a negative film. The eddy current detection method mainly utilizes the electromagnetic induction principle to detect and evaluate the quality of a welding spot through different induced currents generated by a resistance spot welding joint, has high detection sensitivity on surface and near-surface defects, but cannot detect the internal condition of a nugget. The ultrasonic detection method mainly utilizes the difference of the acousticophysical properties of detected materials to evaluate the quality and the performance of the materials. At present, the ultrasonic nondestructive testing of the spot welding quality mainly depends on the positioning of a welding spot by an operator holding a probe, and then the quality of the welding spot is directly evaluated by an ultrasonic detector, so that the automation degree is low, and the requirement on testing personnel is high.
Disclosure of Invention
The invention aims to provide a device and a method for detecting the shape of a spot welding nugget, which can detect the size and the depth of the spot welding nugget.
The technical scheme adopted by the invention for solving the technical problems is as follows: the detection device comprises a plurality of magnetic sensors and a calculation module, wherein the magnetic sensors are arranged in an array form of m rows and n columns, the size of the array form of the magnetic sensors is larger than that of a spot welding nugget to be detected, the magnetic sensors are used for detecting magnetic induction intensity, and the calculation module determines the shape of the nugget according to the magnetic induction intensity detected by each magnetic sensor and calculates the parameters of the nugget.
When the calculation module determines the shape of the weld nugget according to the magnetic induction intensity detected by each magnetic sensor, the magnetic induction intensity detected by the plurality of magnetic sensors is drawn into a contour map of the magnetic induction intensity, wherein the trough position of the contour map is the center of the weld nugget, and the position where the wave crest or gradient changes gently is the edge of the weld nugget.
When the calculation module calculates the parameters of the welding core, the area surrounded by the edges of the welding core is used as a welding core area, the area of the welding core area is calculated as the area of the welding core, and the depth of the welding core is calculated according to the detection value of the magnetic sensor in the welding core area.
And m and n are both greater than or equal to 5.
The technical scheme adopted by the invention for solving the technical problems is as follows: the detection device for the spot welding nugget form comprises the following steps:
(1) placing the detection device above the spot welding nugget;
(2) acquiring detection results of m × n magnetic sensors, and drawing a contour map of magnetic induction intensity according to the detection results;
(3) taking the trough position of the contour map as the center of the weld nugget, and taking the position with gentle wave crest or gradient change as the edge of the weld nugget;
(4) taking a region surrounded by the edges of the weld nuggets as a weld nugget region, and calculating the area of the weld nugget region;
(5) and calculating the depth of the spot welding nugget according to the detection value of the magnetic sensor in the nugget area.
In the step (5) through
Calculating the depth of the spot welding nugget, wherein rijFor spot-welding the depth of the nugget, mu0For vacuum permeability, BijThe detected value of any magnetic sensor in the nugget region, BsijIs a magnetic field generated at the boundary of the nugget and the base material due to material difference and stress, and theta is a magnetic field B at the boundary of the spot welding nugget and the base materialsijUntil the detection value is BijAngle between the position vectors of the magnetic sensors, BCenter of a shipThe value is detected at the center of the array of the plurality of magnetic sensors, and K is a correction coefficient.
A center detection value of the array of the plurality of magnetic sensors
Advantageous effects
Due to the adoption of the technical scheme, compared with the prior art, the invention has the following advantages and positive effects: when the detection device is used for detection, the detection device only needs to be arranged at the upper part of the spot welding nugget without moving, the size and the depth of the spot welding nugget can be directly obtained by utilizing the magnetic induction intensity of the detection device at a fixed position, the noise interference caused by the movement of the sensor is avoided, and the whole detection process is easy to realize automation. The detection method adopted by the invention is a passive magnetic detection method, active excitation is not needed, the weight and the size of a detection instrument can be greatly reduced, the stability of the instrument is also improved, in addition, the size of the detection device can be equivalent to the diameter of a spot welding nugget, and the miniaturization is realized.
Drawings
FIG. 1 is a schematic view of a sensor array structure in a detecting device according to a first embodiment of the present invention;
fig. 2 is a schematic diagram of a row or a column of sensor detection values in the detection device according to the first embodiment of the present invention;
fig. 3 is a contour diagram of magnetic induction intensity plotted by the calculation module in the detection apparatus according to the first embodiment of the present invention.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
A first embodiment of the present invention relates to a spot welding nugget form detection apparatus including a plurality of magnetic sensors and a calculation module.
As shown in fig. 1, the plurality of magnetic sensors are arranged in an array form of m rows and n columns, the size of the array form of the plurality of magnetic sensors is larger than that of a spot welding nugget to be measured, and the magnetic sensors are used for detecting magnetic induction intensity. In the present embodiment, m and n are both odd numbers, and both are equal to or greater than 5. In fig. 1, the number of sensors on the x-axis is: i-1, 2, …, n; the number of sensors on the y-axis is: j is 1,2, …, m; the lower circle is a spot welding nugget.
The detection values of all sensors in the sensor array form a sensor detection value matrix:
wherein B isijIs the detection value of the magnetic sensor.
The detection values of the sensors are sequentially the detection values of the sensors positioned in a certain row or a certain column above the welding core as shown in fig. 2, and the detection values of the plurality of sensors form a curve shape with a downward concave pattern.
The calculation module can determine the shape of the nugget according to the magnetic induction intensity detected by each magnetic sensor and calculate the parameters of the nugget. The method comprises the following specific steps: according to the detection value matrix, detection results of all the m × n magnetic sensors can be drawn into a contour diagram, the position of the lowest point of the contour line is the center of the nugget, the gentle position or the highest position of the contour line is the edge position of the nugget, and information such as the area and the diameter of the nugget can be calculated according to the determined edge position.
As shown in fig. 3, contour lines are drawn based on the detection values of the sensors. The center position of the contour diagram is a center position of the nugget, a valley value exists, a peak strip exists at the edge position of the nugget, and the variation of the detection value of the sensor at the edge position of the nugget is small. The radius of the welding core can be determined according to the trough value position and the wave peak value position, and the range of the welding core can be obtained after the area surrounded by the wave peak values is calculated.
The depth information of the nugget can be calculated from the judged sensor detection value in the nugget region. Because the formation of the spot welding nuggets is a metal melting recrystallization process, the calculation process of the nugget depth information is equivalent to a magnetic source depth solving process. And (3) enabling the magnetic anomaly generated by the target magnetic source to be equivalent to the magnetic induction intensity generated by the current element on the detection surface of the test piece. Magnetic induction component perpendicular to the detection plane according to the Biao-Saval law
Wherein, BCenter of a shipThe central detection value of the array of the plurality of magnetic sensors,
Bij-Bcenter of a shipThe effect of the method is to eliminate the background field around the weld nugget, remove the interference of other magnetic field signals and only keep the influence of the depth of the magnetic source on the sensor. r isijDistance of target magnetic source to sensor, mu0Is a vacuum permeability, BijThe detected value of any magnetic sensor in the nugget region, BsijIs the magnetic field generated by the difference and stress of the materials at the junction of the weld nugget and the base material, and theta is the magnetic field B at the junction of the spot welding weld nugget and the base materialsijUntil the detection value is BijThe angle between the position vectors of the magnetic sensors. Thus, the depth of the magnetic source
K is a correction parameter, and varies depending on the material and the sensor.
Therefore, the diameter range of the weld nugget can be determined according to the contour map, a plurality of magnetic source depths can be obtained by a plurality of sensors in the diameter range of the weld nugget, and parameters such as the depth and the volume of the weld nugget are calculated by utilizing depth information.
It is to be noted that, when one of m and n is an odd number and one is an even number, an average value of the detection values of the two magnetic sensors at the center position of the magnetic sensor array may be used as the center detection value of the magnetic sensor array; when m and n are both even numbers, an average value of the detection values of the four magnetic sensors at the center position of the magnetic sensor array may be used as the center detection value of the magnetic sensor array.
A second embodiment of the present invention relates to a method for detecting a form of a spot welding nugget using the apparatus for detecting a form of a spot welding nugget of the first embodiment, including the steps of:
(1) the magnetic sensor array in the first embodiment is formed by adopting m × n magnetic sensors, wherein m and n are both odd numbers, m is larger than or equal to 5, and n is larger than or equal to 5; the values of m and n can be determined according to the size of the nugget and the size of the sensor.
(2) Placing the formed magnetic sensor array above the spot welding nuggets, and detecting to obtain the detection values of the magnetic sensors;
(3) drawing a contour map of the magnetic induction intensity according to the detection value of the magnetic sensor;
(4) taking the trough position of the contour map as the center of the weld nugget, and taking the position with gentle wave crest or gradient change as the edge of the weld nugget;
(5) and taking the area surrounded by the edges of the weld nuggets as a weld nugget area, and calculating the area of the weld nugget area.
(6) Calculating the depth of the spot welding nugget according to the detection value of the magnetic sensor in the nugget area, wherein the calculation mode is
rijFor the distance of the target magnetic source to the sensor，μ0For vacuum permeability, BijA detection value of any one of the magnetic sensors in the nugget region, BsijIs the magnetic field generated by the difference and stress of the materials at the junction of the weld nugget and the base material, and theta is the magnetic field B at the junction of the spot welding weld nugget and the base materialsijUntil the detection value is BijAngle between the position vectors of the magnetic sensors, BCenter (C)The value is detected at the center of the array of the plurality of magnetic sensors, and K is a correction coefficient.
It is not difficult to find that the detection device adopted by the invention only needs to be arranged at the upper part of the spot welding nugget during detection, does not need to move, can directly utilize the magnetic induction intensity of the detection device at a fixed position to obtain the size and the depth of the spot welding nugget, avoids noise interference caused by the movement of the sensor, and is easy to realize automation in the whole detection process. The detection method adopted by the invention is a passive magnetic detection method, active excitation is not needed, the weight and the size of a detection instrument can be greatly reduced, the stability of the instrument is also improved, in addition, the size of the detection device can be equivalent to the diameter of a spot welding nugget, and the miniaturization is realized.
Claims (4)
1. The device for detecting the form of the spot welding nugget is characterized by comprising a plurality of magnetic sensors and a computing module, wherein the magnetic sensors are arranged in an array form of m rows and n columns, the size of the array form of the magnetic sensors is larger than that of the spot welding nugget to be detected, the magnetic sensors are used for detecting the magnetic induction intensity, and the computing module determines the shape of the spot welding nugget according to the magnetic induction intensity detected by each magnetic sensor and computes the parameters of the spot welding nugget; when the calculation module determines the shape of the weld nugget according to the magnetic induction intensity detected by each magnetic sensor, drawing the magnetic induction intensity detected by the plurality of magnetic sensors into a contour map of the magnetic induction intensity, wherein the trough position of the contour map is the center of the weld nugget, and the position where the wave crest or gradient changes slowly is the edge of the weld nugget; when the calculation module calculates the parameters of the welding core, the area surrounded by the edges of the welding core is used as a welding core area, the area of the welding core area is calculated as the area of the welding core, and the parameters are calculated according to the magnetic sensor in the welding core areaCalculating the depth of the nugget, which passes through
Is calculated to obtain, wherein rijFor spot-welding the depth of the nugget, mu0For vacuum permeability, BijThe detected value of any magnetic sensor in the nugget region, BsijIs the magnetic field generated by the difference and stress of the materials at the junction of the weld nugget and the base material, and theta is the magnetic field B at the junction of the spot welding weld nugget and the base materialsijUntil the detection value is BijAngle between the position vectors of the magnetic sensors, BCenter of a shipThe value is detected at the center of the array of the plurality of magnetic sensors, and K is a correction coefficient.
2. The apparatus for detecting a spot welding nugget form according to claim 1, wherein both of m and n are greater than or equal to 5.
3. A method for detecting a form of a spot welding nugget according to claim 1, wherein the method comprises the steps of:
(1) placing the detection device above the spot welding nugget;
(2) acquiring detection results of m × n magnetic sensors, and drawing a contour map of magnetic induction intensity according to the detection results;
(3) taking the trough position of the contour map as the center of the weld nugget, and taking the position with gentle wave crest or gradient change as the edge of the weld nugget;
(4) taking a region surrounded by the edges of the weld nuggets as a weld nugget region, and calculating the area of the weld nugget region;
(5) and calculating the depth of the spot welding nugget according to the detection value of the magnetic sensor in the nugget area.
4. The method of detecting a form of a spot welding nugget according to claim 3, wherein a center detection value of the array of the plurality of magnetic sensors
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| JP2000351091A (en) * | 1999-06-09 | 2000-12-19 | Topy Ind Ltd | Method and device for detection of weld bead |
| CN102954999A (en) * | 2011-08-19 | 2013-03-06 | 中国石油天然气股份有限公司 | Method for judging signals of triaxial magnetic leakage internal detection line for crack defects of pipeline circumferential welds |
| CN104390579A (en) * | 2014-11-18 | 2015-03-04 | 西安交通大学 | Magnetic sensor array-based welding spatial position detection system and method |
| CN104930965A (en) * | 2015-06-12 | 2015-09-23 | 宁波市鄞州磁泰电子科技有限公司 | Weld joint penetration depth detection method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000351091A (en) * | 1999-06-09 | 2000-12-19 | Topy Ind Ltd | Method and device for detection of weld bead |
| CN102954999A (en) * | 2011-08-19 | 2013-03-06 | 中国石油天然气股份有限公司 | Method for judging signals of triaxial magnetic leakage internal detection line for crack defects of pipeline circumferential welds |
| CN104390579A (en) * | 2014-11-18 | 2015-03-04 | 西安交通大学 | Magnetic sensor array-based welding spatial position detection system and method |
| CN104930965A (en) * | 2015-06-12 | 2015-09-23 | 宁波市鄞州磁泰电子科技有限公司 | Weld joint penetration depth detection method |
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